Has anyone got any experience of the rotors in a stock A4 '98 1.8TQ, and how many pad sets they are good for?
I'm assuming they've been treated normally.
I guess this is the most convenient way of calculating wear without actually measuring their thickness.
Thanks,
JP
What's wrong with measuring their thickness?
Use a micrometer and measure them. Personally, I just replace them each time I change the pads. It's not THAT expensive.
C
There's no such thing as 'normal'. Brake usage is *very* dependent on the individual driver of the car. While I go through a lot more brakes than most people, as a BMW club driving instructor, I'm known for being *easy* on my brakes while colleagues doing the same kind of driving can go through more than a pad set in a single weekend. Although I drive more aggressively on the street than my wife, her brake disks crapped out faster than mine because she didn't use them
*hard enough* (Look up the 'sit rust' syndrome we've discussed here before some time.) Therefore, it's not even completely accurate to make judgments on driving *style*.If you want convenience, just change them every second pad change whether they're down to minimum specs or not. As others have pointed out, it's fairly cheap for the most critical safety system on your car.
-- C.R. Krieger (Been there; fixed that)
Depends on how they're treated. And what kind of pads are being used.
Depends on the definition of "normally." "Normal" for brake use is hardly a fixed quantity.
There really is no substitute of using a cheap tool for the task - this tool is available everywhere (thanks to the Internet,) and is called a "caliper".
Of course, if you are going to the trouble of replacing the pads, may as well just replace the rotors too. They are relatively inexpensive, and the more mass, the better you can stop. If you can afford to run an Audi, you can afford a caliper. Besides, I've found that these babies have a hundred and ten different uses, including stirring paint.
Spider
(Uhh, just kidding on the paint thing.)
A Micrometer is more acurate than Vernier Caliper's, even so, this American method of turning down a set of Disc's
I don't know where you're buying your parts from, but a set of rotors for my 97 A4 costs almost US$200.00
um, no.
A rotor turning typically costs between $5 and $10 per corner.
As long as the rotors are within spec and not warped, this is not an issue.
You're wrong. Stop talking out of your ass.
Hard to say. Even for a Brit - "divided by a common language".
Personally, I suspect "subtlety"
I would guess the UK. Not sure on prices myself (40 quid sounds about right for a set of solid discs, trade, last time I bought a set).
Perhaps one of us nearer where they're made..?[1]
I suspect that we might have a bit of a difference in labour rates - assuming a dismount, align, and remount would take someone about an hour (obviously a lot less if you've already removed the wheel and stripped-out the pads as part of another job) $20-40 a hour sounds a bit low.
As a guide, a franchised dealer rate over here can easily top $150 an hour.
And that they're square[2]. I've once had the misfortune to drive an MGB with turned-down discs. Never again.
Erm. Which bit? That cars with disc brakes were rare in the sixties, that most modern cars come with at least one set of discs, or that most of us are currently inhabiting the 21st century?[4]
Mounting? Alignment? What are you talking about? Those thing have nothing to do with the comparison we're making: the cost of turning vs. the cost of replacement.
If I drive down to my local machine shop, hand them four rotors, and say "turn these", it'll cost less than US$50. Heck, it'll probably be less than US$30.
Any other costs involved in doing the brake job are not relevant, because you need to do them regardless of your decision on the question of resurfacing or replacing.
Everything after "On Tue, 14 Oct 2003 14:58:44 +0100, "Ronny" wrote:"
German rotors don't get turned. They get replaced. Ask your friendly dealer to see their brake lathe. It hasn't been used in a decade.
"JPF" wrote
Ah. You neglected to mention that you had dismounted the discs yourself [i.e. removed then from the car] and used a second vehicle to take then to a non-automotive machine shop. That makes a fair difference in cost..
Well, again, comes down to if you're doing the work yourself.. OTOH, in hindsight, I probably should have guessed this - after all, what company is going to take liability for a set of turned discs, these days?
;o)
Cruel, but amusing, comment.
Incidentally - have you really never experienced any judder after doing this? As I said, my one experience was.. um.. well, "never again". I can't recall how far out it was at the disc edge - not far, IIRC - but it was enough to require disc replacement, pad replacement, and a hour or two checking for consequential damage.. that after limping 20miles to home.
(Just like to reiterate - not my idea to skim the discs; I'd have replaced 'em, given that it was supposed to be a /full/ rebuild of my father's car)
H1K
haha yes British wit, unlike the corny 1 liners from overpaid American actors, where everyone whoops and clap's as they enter a room
Then you are going to the wrong place, check
Oh and look thats Brembo Discs, 21.50 for vented A4, 31.50 for cross drilled
"Sez" you, I will stick to my new disc's thanks
How am I wrong? care to explain,??????
Ron
Thanks to all for your answers. Of course, I do understand the possible problem of rust formation and extreme temperature changes, for example when hitting a pool of water after spirited driving.
However, excepting those and extreme circuit driving, I would still think pad wear must be faithfully proportional to disc wear - after all if pads wear, then so do rotors at a given rate. Now, if we set stock pads and discs as a reference, then it should be possible to do such calculations as 2 or 3 sets. Before I got all your opinions I would have ventured 3 sets but now I realize I was being too optimistic, maybe. Nobody mentioned the thinner the discs - and no I'm not into having them lathe-turned, the worse their heat dissipation capability becomes, which reduces efficiency greatly. So my original question was something like, will 3 sets make the rotors so thin that there will be a noticeable reduction in efficiency?
Of course, now the discussion could turn to aftermarket pads and how efficient they are vs stock, then a difference in the number of sets would sound quite logical to me.
Regards,
JP Roberts
"JP Roberts" escribió en el mensaje news:bmcc0c$e4r$ snipped-for-privacy@news.ya.com...
sigh.
Any difference is irrelevant to the question at hand. All of those things - the dismounting, the replacement, etc - have to happen regardless of whether the rotors are resurfaced or replaced. The rotors don't magically install themselves on the car simply because you purchased new ones, you know.
Now that I say it, that paragraph sounds vaguely familiar...
Oh, there's why ^^^
Rotors should be resurfaced or replaced every time you replace the pads.
(I know some people are going to disagree with me about that. Please, don't bother - you'll only be talking to hear yourself talk.)
Nope.
There's a factory specification for the minimum thickness of the rotors. If the rotors exceed that specification after resurfacing, there's no reason to replace them.
argumentum ad hominem, blah blah blah
How many wheels does your car have?
34.50 +34.50 +34.50 +34.50-------------
138.00...and that's pounds, so US$229.89
I notice, hoever, that GBP$34.50 is around US$57.50, which is pretty close to your original estimate. Perhaps this is another language difference. In Great Britian, is "set" defined as "one"?
Hey man, it's your money.
Asked and answered.
As I have already demonstrated using the magic of "math" it is cheaper to resurface the rotors than it is to replace them.
I am of the opinion, based on my experience, that there is no harm in resurfacing rotors provided that they exceed the factory specification. You might disagree with that. I do not care. Your opinion doesn't change the fact that it is cheaper to resurface the rotors than it is to replace them.
After experiance JP I would say you should get 2 sets of pads per 1 disc, I use cross Drilled and vented Disc's on my A4 Quattro, and have done 40k miles on 1 set of pads and they still look fine. I drive it fairly hard, but more motorway miles then stop start.
If you can, get yourself some Zimmerman Cross Drilled disc's and some Pagid Fast road pads, change the lot all round 4 discs and 2 sets of pads.
The cost for me was £100.00 per axle thats $150 approx, if you require cheaper stuff, than go with OEM, but A4 brakes are terrible at best, the upgrade really is worth it ..
hth
Ron
Actually, I sorta did:
"They [new rotors] are relatively inexpensive, and the more mass, the better you can stop."
Spider
Right Spider
"Spider" escribió en el mensaje news: snipped-for-privacy@posting.google.com...
Apparently, you don't, really. The rust I mentioned comes from letting the car sit parked outside overnight where condensation (dew) forms on the rotors, forms drips on the inside and outside edges, rusts in those areas, and is insufficiently cleared the following day because the driver's normal braking pattern is too tentative or gentle. The rust then slowly starts cutting away the surface of the pad (it's harder than the pad) and the pad gets progressively worse at clearing the rust which obviously continues cutting away more pad. Quite a nasty syndrome that's easily addressed by braking more aggressively to be sure to knock off all the rust daily. Driving through water has almost nothing to do with it. The greatest problems with rust on rotors come from the car *sitting*, not being driven.
For an individual driver, that's correct, but some drivers can still extend their pads' lives by 'smart braking', so your mileage *still* may vary.
Fair enough. Two sets isn't a bad rule of thumb.
Good thinking.
Like PBR Deluxe pads ...
-- C.R. Krieger "Ignore 'em, m'dear; they're beneath our dignity." - W.C. Fields
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